Play from Either Hand

Q 9 6 2
A K 8 5
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A K 5 4 2
J 8 3 10 4
J 4 3 Q 10 9 6 2
A 9 8 3 K 10 7 2
Q 7 6 8 3
A K 7 5
7
Q J 6 5 4 Contract: 6 spades
J 10 9Opening Lead: A of diamonds, 3 of hearts

I fell kinda flat on my face the first time I entered this one. I thought it was a matter of taking a natural finesse, which the declarer who went down didn't take. Two people who made an overtrick did take the finesse, and I rather hastily concluded that it was a failure to take the finesse than spelled this declarer's downfall. It was only as I was typing up the way the hand played out that I saw that the finesse or failure to take it had nothing to do with going down, but rather with an overtrick. No overtrick without the finesse, but no undertrick either if one plays the rest of the hand right.
Both declarers who made an overtrick got the ace of diamonds on opening lead. Now let's count out losers from the closed hand, and we find that we may or may not lose a club, hearts are cool, so are the trump on a 3-2 split, and we've got 5 diamonds to take care of. Well, two can go on the club differential, regardless of whether the finesse loses or not, one can go on the second round of hearts, and so we need to ruff two diamonds if we hope to make 7, or perhaps 6 on a losing club hook. And we've got one diamond ruff under our belt already.
So we've just gotta get one more diamond ruff in, draw a third round of trump and go after the club hook. Declarers cashed the queen of spades, came to the ace of spades, took the club hook, and when when the finesse held, now declarer ruffs a second diamond, cashes the ace of hearts, ruffs a heart, cashes out the last round of trump, sluffing a heart and now dummy is good. West could have given declarer a scare of sorts by covering the club honor, first round. Declarer would have been in the wrong hand for ruffing another diamond, and you don't like to take too many rounds in an 8-card side suit before trump are out, but the cards are friendly, and declarer could only have come back on a club lead, then ruffed a second diamond, then cashed a top heart, ruffed a heart, led a third round of trump, sluffing a heart, and dummy is now good on a club lead.
Here's the play of the declarer who went down. Opening lead a heart, taken in dummy, a heart was ruffed. I thought declarer was making a serious mistake, and I typed out this italicized message. Don't cash out established winners you've always got access to unless you have a positive reason to. It turned out that the advice wasn't bad. I was merely saying it too soon, in relation to the wrong trick as you'll see.
Declarer now cashed the A K of trump and ruffed a diamond. Ruffed a diamond! That's the trick I should have applied that stricture to. At that point, she knows trump are splitting 3-2, she always has dummy's fourth trump coming to her and had no reason to cash that valuable entry here. The fact is, she was substantially but not altogether playing a dummy reversal, and that was her downfall, that it wasn't completely so. She's ruffing hearts in the closed hand and diamonds in the open, and that was her downfall. She has to play from one hand or the other, set up one hand or the other. She could easily have made the hand on dummy reversal and made it without the finesse, thus: Ruff a heart at trick two, cash A K of trump, go to the ace of clubs, ruff another heart, then back to the king of clubs, draw the last trump out and concede a club. Dummy would then be good with the last trump, the only clubs and a high heart.
That line doestn't give us an overtrick, of course. But I would not critique declarer either for taking that finese or declining to take it. However, in counting out losers from dummy, she would see that diamonds are out of it. Forget 'em. Clubs will be established with or without a finesse. Her primary task is to take care of those two small hearts, which she did very well. Only, she should not have shorted dummy's rather skimpy trump holding. As soon as the second heart was ruffed, her task was to get back to dummy in the most expeditious manner possible, draw the defense's last trump, concede a club if the finesse wasn't taken and claim.
If the hand was played out, you would be sluffing a diamond on the third round of trump. It's the same trick. Only now you draw the last trump held by the defense and save your last trump for access to the clubs and as a diamond stopper if you eschew the finesse (or if it should lose). You've always got that trick coming when you see trump are 3-2.

Which line of attack is better? It looks to me as if the opponents have a hand in deciding that. The opening diamond lead puts the declarer within one diamond ruff of accounting for the closed hand, while an opening heart lead puts declarer in a pretty good position to play it in a dummy reversal.